Direct Recycling Research Articles

High-power ultrasound facilitation of the generality for LiFePO4 regeneration

Renowned for its remarkable electrochemical performance, temperature stability, safety attributes, and long-lasting durability, the LiFePO4 battery has gained prominence in diverse applications, particularly within the electric vehicle sector. Despite not holding the top market position, approximately 69 % of global batteries comprise LiFePO4, raising concerns about a potential increase in discarded batteries. Present research predominantly concentrates on extracting valuable materials such as Co, Li, Ni, and Mn, frequently sidelining spent LiFePO4 batteries due to their perceived limited recoverable content compared to NMC and LCO batteries. However, LiFePO4 batteries removed from electric vehicles retain approximately 80 % of their initial capacity, with the cathode material sustaining a robust crystal structure. Here, direct recycling techniques employing a green reducing agent like ascorbic acid have shown promise in rectifying lithium vacancies and anti-sites in spent LiFePO4 through high power ultrasonic reactions. This work delves into exploring the influence of different lithium sources and Li + concentrations on the structure and electrochemical performance of regenerated LiFePO4. The direct regeneration of LiFePO4 showcases a favorable crystal structure that maintains stable phase transitions during charge and discharge processes. RLFP-0.2 M exhibits discharge specific capacity of 154.71 mAh∙g−1. It indicates RLFP-0.2 M maintains a discharge specific capacity of 132.89 mAh∙g−1 after 200 cycles at 1C current, retaining a remarkable capacity retention rate of 93.56 %. This study demonstrates that high-power ultrasonication is a universally applicable, low-energy, highly efficient, operationally simple, and environmentally friendly method for direct recycling of spent LiFePO4 batteries. Our research not only investigates the influence of various lithium sources and Li + concentration but also optimizes the recycling process for spent LiFePO4 batteries. Additionally, it provides an experimental foundation and reference for the recycling of other power batteries, contributing to achieving green direct recycling of various power batteries.

Application and recycling of lithium-ion batteries

As an emerging technology with a vast worldwide market application and potential over decades, electric vehicles (EVs) have played a significant role in human society to prevent the deterioration of the environment. Meanwhile, the research on lithium-ion batteries (LIBs) in EVs improving their performances, including energy density and cycle life, has recently attracted much attention, aiding the further development of the functions of EVs. This research can be divided into three parts. Firstly, the fundamental of LIBs is presented, including its theory and reasons for having low energy density. Then, the alternative Li-S battery technology employed for EVs is introduced, and its advantages and limitations for future research are illustrated. Lastly, the three main approaches for recycling used LIBs, pyrometallurgical recovery (Pyro.), hydrometallurgical metals reclamation (Hydro.) and direct recycling (Dir.) are elaborated, each of their strengths and weaknesses are shown, and their performances are compared by considering several aspects for selection.

Green recycling assessment on typical spent lithium-ion batteries (LIBs): A multi-objective assessment

Recycling of spent lithium-ion batteries (LIBs) is an efficient solution for resource supply crisis and severe environmental pollution. However, the comprehensive evaluation on resource criticality and environmental impact were neglected in the life cycle assessment (LCA). In this study, a green recycling assessment methodology was proposed associated with raw material criticality assessment, system operation elements analysis and comprehensive environmental assessment (CEA). The hydrometallurgical, pyrometallurgical and direct recycling process of lithium nickel manganese cobalt oxide (NMC) and lithium iron phosphate (LFP) were selected as 6 typical recycling processes. Under the multi-objective assessment, the green recycling grades (G) was classified into 10 grades, and the direct recycling process of NMC and LFP were the two greenest recycling processes with the G value of 9.66 and 9.58. According to the assessment results of this study, direct recycling process was the best recycling process due to the less the consumption of substance and production of waste. This research established the green recycling assessment methodology for spent LIBs, which could guide the green development of spent LIBs recycling industry.

Effective upcycling of NMC 111 to NMC 622 cathodes by hydrothermal relithiation and Ni-enriching annealing

It is imperative that a sustainable approach to the recycling of lithium-ion batteries (LIBs)—in particular the spent NMC cathodes—which reach their end-of-life (EOL) is realized as 11 million metric tonnes are expected to reach EOL by 2030. The current recycling processes based on pyrometallurgy and hydrometallurgy are not fully sustainable options as they recover only the value metals. By contrast direct recycling that aims in regenerating EOL LIB cathodes without breaking down the active compound’s crystal structure offers the most sustainable option. In this paper the direct recycling of NMC cathodes is investigated in combination with their upcycling. Upcycling is going to be in growing demand since the first generation NMC 111 cathode chemistries evolve to higher energy/nickel-rich formulations. In this work, the baseline is established for direct recycling of low and high nickel NMC cathodes by analyzing the three key steps of chemical delithiation of pristine NMC cathode material, hydrothermal relithiation (4M LiOH for 4 h at 220 °C), and annealing (4 h at 850 °C) in order to set the ground for investigating the upcycling of NMC 111 to NMC 622. Upcycling is affected via the co-addition of pre-calculated excess NiSO4 and Li2CO3 salts during annealing, following the hydrothermal relithiation step. Use of NiSO4 that is commonly used as p-CAM provides a lower cost alternative to Ni(OH)2 as Ni source. Characterization revealed the upcycled material to have been endowed with the typical α-NaFeO2 layered structure and have surface morphology and composition similar to pristine NMC material. The upcycled NMC 622 cathode yielded good cycling stability (91.5% retention after 100 cycles) and >99% Coulombic efficiency albeit with certain polarization loss justifying further optimization studies.

Resource Recovery of Spent Lithium-Ion Battery Cathode Materials by a Supercritical Carbon Dioxide System.

The increasing global market size of high-energy storage devices due to the boom in electric vehicles and portable electronics has caused the battery industry to produce a lot of waste lithium-ion batteries. The liberation and de-agglomeration of cathode material are the necessary procedures to improve the recycling derived from spent lithium-ion batteries, as well as enabling the direct recycling pathway. In this study, the supercritical (SC) CO2 was innovatively adapted to enable the recycling of spent lithium-ion batteries (LIBs) based on facilitating the interaction with a binder and dimethyl sulfoxide (DMSO) co-solvent. The results show that the optimum experimental conditions to liberate the cathode particles are processing at a temperature of 70 °C and 80 bar pressure for a duration of 20 min. During the treatment, polyvinylidene fluoride (PVDF) was dissolved in the SC fluid system and collected in the dimethyl sulfoxide (DMSO), as detected by the Fourier Transform Infrared Spectrometer (FTIR). The liberation yield of the cathode from the current collector reaches 96.7% under optimal conditions and thus, the cathode particles are dispersed into smaller fragments. Afterwards, PVDF can be precipitated and reused. In addition, there is no hydrogen fluoride (HF) gas emission due to binder decomposition in the suggested process. The proposed SC-CO2 and co-solvent system effectively separate the PVDF from Li-ion battery electrodes. Thus, this approach is promising as an alternative pre-treatment method due to its efficiency, relatively low energy consumption, and environmental benign features.

Subtle differences in recycled polypropylene from rheology to additives impacts ease of circularity in materials extrusion additive manufacture

The decentralized production associated with material extrusion additive manufacture (MEX) has been proposed as an ideal path to increase the circularity of plastics through direct recycling. Although multiple studies have reported on the 3D printing of various recycled plastics, variability in recycled materials, in particular post-consumer waste, challenges the direct extension of these results into production through MEX. Here, we demonstrate filament fabrication and printing of post-consumer polypropylene (PP), where the PP is sourced from clear, cold drink cups from three large international food service and beverage retail chains to provide well defined plastic waste that is perfectly sorted for recycling. These sources for the recycled PP were selected due to their ready availability to enable the results to be directly applied for hobbyist printing, blow molded products to provide good mechanical performance, and the clarity of the PP that suggests formulation design to minimize the PP crystal size. Despite the similarities in the end use product and their physical appearance, the source for the PP impacted the mechanical properties and the visual appearance of the printed objects. These differences can be directly traced to the rheological properties and oxidative stability of the PP at conditions relevant with the print process. These results clearly illustrate differences in initial formulation design and branding details, even when the product is for the same application, impacts the performance of recycled plastics in AM. The high viscosity associated with the PP from blow molding leads to requirements for higher extrusion temperatures for printing. The combination of high temperature and shear during extrusion process of 3D printing degrades the recycled PP. For circularity with MEX with recycled PP, one needs to consider the evolution in the properties of the polymer. Rheological details of recycled plastics are critical to selection of processing conditions and performance of MEX parts. Reporting of rheological data of recycled plastics and these properties after printing is critical to enable translation towards circular 3D printing of recycled plastics.

Atomic hydrogen production in a cold plasma for application in a metal foil pump

Any good design of fuel cycles for thermonuclear fusion reactors, which operate on deuterium-tritium fusion, comes with minimized tritium inventory. The direct internal recycling concept can significantly reduce the tritium inventory of a fusion power plant by introducing a bypass for most of the unburned fuel from the torus exhaust. It requires a technology that can sharply separate hydrogen isotopes from other gases in the given environment in the reactor's pump duct. The prime candidate for this task is a metal foil pump (MFP) using plasma-driven permeation. A workflow toward a performance predicting modeling tool of a MFP is introduced. It is based on the characterization of the employed cold plasma by using a plasma simulation, which is experimentally validated using optical emission spectroscopy and the actinometry method. The used approach accounts for the radial inhomogeneity of the linearly extended plasma. We determine the atomic hydrogen content down to pressures of 1 Pa and condense the complex processes that contribute to the hydrogen atom production into a single excitation probability. This value can be used in Monte Carlo based modeling approaches to determine the particle exhaust performance of the vacuum pump.

The Impact of Heating Temperature and Flux Ratio on the In-Situ Casting Technique as a Direct Recycling of AlSi7Mg Machining Chips

Recycling aluminium and its alloys is gaining popularity in reducing energy consumption and associated manufacturing expenses. The fluxing process is the preferred and often-used technique in the recycling sector for removing oxide inclusions from molten aluminium. The present study investigates the influence of flux ratio and heating temperature on the behaviour of aluminium alloy chips (AlSi7Mg) during in-situ casting. The primary objective is to create a more efficient and economical approach to recycling aluminium waste. The chips underwent heating for 30 minutes inside a controlled laboratory furnace. The temperatures used during this procedure were 750°C and 800°C. The chips were combined with flux in ratios of 1:0.1 and 1:0.2. The number of melted chips rose due to increasing the temperature and flux ratio. The heated samples were subjected to surface morphology and elemental analysis using a scanning electron microscope with energy-dispersive spectroscopy (EDS). The Energy Dispersive Spectroscopy (EDS) examination indicated the presence of oxygen on the surface of the unprocessed aluminium alloy machining chips. On the other hand, the X-ray diffraction (XRD) revealed that the observed condition may be attributed to the oxidation process, proven by the presence of Aluminium Oxide (Al2O3).

Optimizing strength of directly recycled aluminum chip-based parts through a hybrid RSM-GA-ANN approach in sustainable hot forging.

Direct recycling of aluminum waste is crucial in sustainable manufacturing to mitigate environmental impact and conserve resources. This work was carried out to study the application of hot press forging (HPF) in recycling AA6061 aluminum chip waste, aiming to optimize operating factors using Response Surface Methodology (RSM), Artificial Neural Network (ANN) and Genetic algorithm (GA) strategy to maximize the strength of recycled parts. The experimental runs were designed using Full factorial and RSM via Minitab 21 software. RSM-ANN models were employed to examine the effect of factors and their interactions on response and to predict output, while GA-RSM and GA-ANN were used for optimization. The chips of different morphology were cold compressed into billet form and then hot forged. The effect of varying forging temperature (Tp, 450-550°C), holding time (HT, 60-120 minutes), and chip surface area to volume ratio (AS:V, 15.4-52.6 mm2/mm3) on ultimate tensile strength (UTS) was examined. Maximum UTS (237.4 MPa) was achieved at 550°C, 120 minutes and 15.4 mm2/mm3 of chip's AS: V. The Tp had the largest contributing effect ratio on the UTS, followed by HT and AS:V according to ANOVA analysis. The proposed optimization process suggested 550°C, 60 minutes, and 15.4 mm2 as the optimal condition yielding the maximum UTS. The developed models' evaluation results showed that ANN (with MSE = 1.48%) outperformed RSM model. Overall, the study promotes sustainable production by demonstrating the potential of integrating RSM and ML to optimize complex manufacturing processes and improve product quality.

Fast Li Replenishment Channels-Assisted Recycling of Degraded Layered Cathodes with Enhanced Cycling Performance and Thermal Stability.

The direct recycling of cathode materials in lithium-ion batteries is important for environmental protection and resource conservation. The key regeneration processes are composition replenishment and atom rearrangement, both of which depend on the migration and diffusion of atoms. However, for the direct recycling of degraded LiNi0.5 Co0.2 Mn0.3 O2 (D-NCM523) cathode, the irreversible phase transitions that accumulate during the long-term cycles block the Li diffusion channels with a high diffusion energy barrier, making it difficult to fully repair the layered structure and resulting in rapid capacity decay. To address the challenge, fast Li replenishment channels are rebuilt to regulate the surface phase and effectively assist the regeneration process with a reduced energy barrier. This method reduces the amount of Li supplement by >75% and shortens the sintering time (only 2h) to fully regenerate D-NCM523, compared to general direct recycling methods. The regenerated NCM523 (LCMB-NCM523) exhibits a satisfactory repaired specific capacity of 160mAhg-1 and excellent cycling stability, retaining 78% of its capacity after 300 cycles. In addition, LCMB-NCM523 is recycled with improved thermal decomposition peak temperature and enables 200 cycles even at 60°C, greatly improving safety. This work proposes a promising way for the large-scale direct regeneration of layered cathodes.

Life cycle assessment of direct recycling hot press forging of aluminium AA7075 metal matrix composite

The primary objective of this research is to investigate the process of direct recycling of AA7075 aluminium alloy, which is extensively utilised in the aerospace and flight sectors due to its exceptional strength and lightweight characteristics. Alumina (Al2O3) is used as a reinforcing agent and the effect of hot press forging (HPF) parameters on the mechanical characteristics and surface integrity of the metal matrix composite (MMC) constructed of AA7075 alloy with 1% Al2O3 has been studied. Furthermore, the utilisation of an integrated life cycle assessment (LCA) approach is implemented to assess the environmental impacts and economic expenses associated with the recycling of aluminium via high-pressure forming for both the metal matrix composite and AA7075 alloy. Response surface methodology (RSM) is applied to ascertain the optimal parameters for high-performance filtration. The findings suggest that employing a forging temperature of 532.34 °C and a holding time of 60 min produces favourable results. When comparing the characteristics of the MMC and recycled aluminium, it can be observed that they both demonstrate similar essential process attributes. The utilisation of HPF in conjunction with the Multi-Material Composite has the potential to yield a reduction of up to 24.97% in Global Warming Potential (GWP). This research demonstrates the efficacy of HPF as a viable approach for environmentally conscious and economically efficient recycling of AA7075 aluminium scrap, thereby improving product performance and promoting sustainability.

Toward Direct Regeneration of Spent Lithium-Ion Batteries: A Next-Generation Recycling Method.

The popularity of portable electronic devices and electric vehicles has led to the drastically increasing consumption of lithium-ion batteries recently, raising concerns about the disposal and recycling of spent lithium-ion batteries. However, the recycling rate of lithium-ion batteries worldwide at present is extremely low. Many factors limit the promotion of the battery recycling rate: outdated recycling technology is the most critical one. Existing metallurgy-based recycling methods rely on continuous decomposition and extraction steps with high-temperature roasting/acid leaching processes and many chemical reagents. These methods are tedious with worse economic feasibility, and the recycling products are mostly alloys or salts, which can only be used as precursors. To simplify the process and improve the economic benefits, novel recycling methods are in urgent demand, and direct recycling/regeneration is therefore proposed as a next-generation method. Herein, a comprehensive review of the origin, current status, and prospect of direct recycling methods is provided. We have systematically analyzed current recycling methods and summarized their limitations, pointing out the necessity of developing direct recycling methods. A detailed analysis for discussions of the advantages, limitations, and obstacles is conducted. Guidance for future direct recycling methods toward large-scale industrialization as well as green and efficient recycling systems is also provided.

Direct recycling of Li‐ion batteries from cell to pack level: Challenges and prospects on technology, scalability, sustainability, and economics

AbstractDirect recycling is a novel approach to overcoming the drawbacks of conventional lithium‐ion battery (LIB) recycling processes and has gained considerable attention from the academic and industrial sectors in recent years. The primary objective of directly recycling LIBs is to efficiently recover and restore the active electrode materials and other components in the solid phase while retaining electrochemical performance. This technology's advantages over traditional pyrometallurgy and hydrometallurgy are cost‐effectiveness, energy efficiency, and sustainability, and it preserves the material structure and morphology and can shorten the overall recycling path. This review extensively discusses the advancements in the direct recycling of LIBs, including battery sorting, pretreatment processes, separation of cathode and anode materials, and regeneration and quality enhancement of electrode materials. It encompasses various approaches to successfully regenerate high‐value electrode materials and streamlining the recovery process without compromising their electrochemical properties. Furthermore, we highlight key challenges in direct recycling when scaled from lab to industries in four perspectives: (1) battery design, (2) disassembling, (3) electrode delamination, and (4) commercialization and sustainability. Based on these challenges and changing market trends, a few strategies are discussed to aid direct recycling efforts, such as binders, electrolyte selection, and alternative battery designs; and recent transitions and technological advancements in the battery industry are presented.

Direct Recycling Technology for Spent Lithium-Ion Batteries: Limitations of Current Implementation

The significant deployment of lithium-ion batteries (LIBs) within a wide application field covering small consumer electronics, light and heavy means of transport, such as e-bikes, e-scooters, and electric vehicles (EVs), or energy storage stationary systems will inevitably lead to generating notable amounts of spent batteries in the coming years. Considering the environmental perspective, material resource sustainability, and terms of the circular economy, recycling represents a highly prospective strategy for LIB end-of-life (EOL) management. In contrast with traditional, large-scale, implemented recycling methods, such as pyrometallurgy or hydrometallurgy, direct recycling technology constitutes a promising solution for LIB EOL treatment with outstanding environmental benefits, including reduction of energy consumption and emission footprint, and weighty economic viability. This work comprehensively assesses the limitations and challenges of state-of-the-art, implemented direct recycling methods for spent LIB cathode and anode material treatment. The introduced approaches include solid-state sintering, electrochemical relithiation in organic and aqueous electrolytes, and ionothermal, solution, and eutectic relithiation methods. Since most direct recycling techniques are still being developed and implemented primarily on a laboratory scale, this review identifies and discusses potential areas for optimization to facilitate forthcoming large-scale industrial implementation.

Resonant Acoustic Vibration-Assisted Cathode Stripping for Efficient Recycling of Spent Li-Ion Batteries

Abstract The emerging field of direct recycling for spent Li-ion batteries offers significant advantages, such as reduced energy expenses and minimized secondary pollution, when compared to traditional pyrometallurgical and hydrometallurgical methods. This is due to its direct utilization of the spent cathodes as raw materials. However, efficient harvesting of spent cathode particles remains a challenge. To address this issue, this technical brief is the first to incorporate resonant acoustic vibration technology (RAV) as an efficient method for stripping cathode powders from spent Li-ion batteries. Our findings indicate that RAV-based techniques can achieve a stripping efficiency of up to 92%. A comparative analysis with conventional stripping methods, such as magnetic stirring, sonication, and curling–uncurling, reveals that RAV coupled with heat treatment provides unparalleled scalability and efficiency, eliminating the need for post-processing. Furthermore, the resulting cathode powders retain their original polycrystalline particle structures, with no impurities, such as carbon black or small aluminum fragments detected. These findings highlight the promise of RAV technology for large-scale recovery of electrode powders and its potential role in direct recycling of spent Li-ion batteries.

Life cycle assessment of secondary use and physical recycling of lithium-ion batteries retired from electric vehicles in China

With the rapid development of the global new energy vehicle industry, how to minimize the environmental impact of the recovery has become a common concern and urgent concern. China is a major production and consumption market for electric vehicles, there are no specific and extensive resource and environmental assessment system for batteries. In this paper, the retired Electric vehicles lithium-ion batteries (LIBs) was the research object, and a specific analysis of the recycling treatment and gradual use stages of power batteries were based on life cycle assessment. Different battery assessment scenarios were established according to the development of battery recycling in China. The results showed that the secondary use has the optimal performance compared to the full-component physical, pyrometallurgical and hydrometallurgy recycling. The results showed that direct recycling has a GWP of 0.037 kg-CO2 eq·kg LIB-1, which is lower than others. Secondary use of LIB accounts for the most emission reductions with Global warming (GWP) as 12.134 kg-CO2 eq·kg LIB-1. The secondary use has the greatest impact on the assessment results, especially in dynamic scenarios. Through a comprehensive comparison of different recycling technologies, the secondary use, increasing the recycling rate, reducing resource, energy consumption and pollution emissions.

Efficient direct repairing of lithium- and manganese-rich cathodes by concentrated solar radiation

Lithium- and manganese-rich layered oxide cathode materials have attracted extensive interest because of their high energy density. However, the rapid capacity fading and serve voltage decay over cycling make the waste management and recycling of key components indispensable. Herein, we report a facile concentrated solar radiation strategy for the direct recycling of Lithium- and manganese-rich cathodes, which enables the recovery of capacity and effectively improves its electrochemical stability. The phase change from layered to spinel on the particle surface and metastable state structure of cycled material provides the precondition for photocatalytic reaction and thermal reconstruction during concentrated solar radiation processing. The inducement of partial inverse spinel phase is identified after concentrated solar radiation treatment, which strongly enhances the redox activity of transition metal cations and oxygen anion, and reversibility of lattice structure. This study sheds new light on the reparation of spent cathode materials and designing high-performance compositions to mitigate structural degradation.

Scalable direct recycling of spent LiNi1/3Co1/3Mn1/3O2 via in-situ elements replenishment and structural restoration

The proliferation of vehicles and portable devices has led to a significant increase in the number of spent lithium-ion batteries (LIBs). Recycling these spent LIBs is crucial to prevent negative environmental impacts and resource wastage. However, traditional pyrometallurgical and hydrometallurgical methods suffer from inherent drawbacks as being time-consuming, energy-intensive and causing secondary pollution. Herein, an innovative approach is proposed to direct regenerate degraded LiNi1/3Co1/3Mn1/3O2 (NCM111) in-situ by combining hydrothermal treatment with solid-state sintering. Structural and morphology characterizations reveal that the amorphous layer near the surface of degraded NCM111 (D-NCM111) are dissolved after the hydrothermal treatment, restoring the original layered structure due to the relithiation reaction, whereas the target stoichiometric ratios of transition metal elements are achieved through the solid-state sintering process. The regenerated NCM111 (R-NCM111) exhibits a high discharge specific capacity of 152.3 mAh/g at 0.1 C and a capacity retention of 96.1% at 1 C after 300 cycles. The recycling method presented in this work is not only facile but also scalable, potentially opening a new pathway to address the environmental challenges posed by massive spent LIBs.

Effect of pressing pressure on the capacity of recycled graphite anode

AbstractDue to the increasing demand for lithium-ion batteries, there is an urgent requirement for environmentally friendly and efficient means of recycling these batteries. Graphite, a readily available and cost-effective material, tends to be neglected compared to more expensive metals such as cobalt or nickel. To achieve the new European targets, it will be necessary to focus on recycling even less valuable materials, such as graphite. Direct recycling of graphite represents an environmentally and economically viable solution. However, the capacity of recycled graphite depends on several factors, with pressing pressure being a potential variable. Within this article, we have focused on the impact of pressing pressure of spent graphite anode. The recycling was performed on the battery sample with a known lifetime history. It was found that when optimized, it is possible to achieve high stability and high capacities exceeding 300 mAh/g. Graphical abstract

Recycling of beryllium swarf for the preparation of Be/Al composites with high mechanical properties by pressure infiltration method

Utilizing recycled beryllium swarf and aluminum, Be/Al composites containing varying volume fractions of beryllium were fabricated via the pressure infiltration method, which realized the direct and green recycling of beryllium swarf without dust. This study systematically investigates the microstructure and mechanical properties of Be/Al composites. Under pressure infiltration conditions, the molten aluminum successfully repaired the defects in the beryllium swarf. Additionally, the serrated morphology of the swarf increased the contact area between the beryllium swarf and aluminum matrix, enhancing interfacial bonding strength. As the volume fraction of beryllium swarf increased, the tensile strength, yield strength, and elastic modulus of the composite material increased, while elongation exhibited a different trend. Considering the service conditions of the material, 60% volume fraction is the optimal parameter. The fracture of Be/Al composites comprised both ductile fracture of the Al phase and brittle fracture of the Be phase. The debonded surface of beryllium swarf reinforcement was generally smooth rather than densely cracked or large serrated.